1. Technical Field
The present invention relates to a wireless communication method for use with a wireless communication system constituted by a plurality of wireless communication apparatuses and to wireless communication apparatuses that composes the wireless communication system.
2. Background Art
A system constituted of a base apparatus and a display terminal has been developed. The base apparatus functions as an information source or as an access point in which or to which a television broadcast receiving tuner is built or connected and that is connected to a telephone line through a modem as one type of a wireless LAN system that is structured in a limited area of a residence, an office, or the like. The display terminal executes functions for issuing a command to the base apparatus through a wireless communication with the base apparatus that includes receiving a picture of the television from the base apparatus, receiving information from the Internet, displaying the picture and information on a display, and transmitting and receiving electronic mail through the base apparatus.
As radio frequency bands that can be used for the wireless communication system, the IEEE 802.11a standard has defined a 5.8 GHz band (in U.S. a 5.2 GHz band, these bands are generally called 5 GHz band), whereas the IEEE 802.11b standard has defined a 2.4 GHz band.
When a wireless communication system deals with both the 5.2 GHz band and the 2.4 GHz band, it can perform a communication over a radio channel (radio frequency) properly selected as a communication channel from the 5.2 GHz band and 2.4 GHz band.
However, in a communicable area of the above-described wireless communication system, another wireless communication system of the same type as the present system or of a different type, such as Bluetooth (a registered trademark), that uses the same frequency bands as the present system might coexist.
In addition, if another system coexists with the present system, a communication radio wave of the other system may become a disturbing wave that causes data streams to be broken, moving pictures streams to be stopped, and images to be disturbed with respect to the data transmission in the present system.
Also, besides those wireless communication systems that interfere with the present system, there may be, for example, microwave ovens and so forth in the vicinity of the present system. When such a device radiates a radio wave of the radio frequency band that the present system uses, the radio wave may act as a disturbing wave and adversely affect the present system.
Furthermore, when a large volume of data, such as picture data from the television and moving picture data of the Internet, are transmitted, it would be desirable to increase the data transmission rate.
However, in the 5.2 GHz band defined in the IEEE 802.11a standard, the maximum transmission rate can be increased up to at most 54 M bps (mega bits/second). In contrast, in the 2.4 GHz band defined in the IEEE 802.11b standard, the transmission rate can be increased up to at most 11 Mbps.
If the transmission rate at which a large volume of data, such as picture data and moving picture data, is transmitted is low, it might be difficult to securely and smoothly transmit the data in a real time basis.